Spark-plug.



G. 0. TERRY.

SPARK PLUG.

APPLICATION FILED una. 1911.

1,009,286?, Patented N0v.28, 1911.

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Q/vhw PWA Sttomwgs UNITED sTATEs PATENT oEEioE.

GEORGE ORVILL TERRY, 0F MINNEAPOLIS, MINNESOTA.

SPARK-PLUG.

Specicaton of Letters Patent. Patented NOV, 28, 1911, Application 'filed.April 3, 1911.

in the art to which it 'appertains to inalieand use the saine.

This invention relates to improvements in spark plugs for internalcombustion engines and .more particularly to improvements in what inaybe termed jump spark igniting plugs.

The object of the invention is to provide a simply constructed plughaving a large smooth sparking surface and so constructed as to reducethe danger' of short circuiting to the minimum.

Another object of the invention is to provide a plug of this characterin which the electrodes are spaced the saine distance at all points topermit the current to jump across at any point of the periphery of thecenter electrode.

` Another object is to provide interchange-r able electrodes by the useof which the life of the plug is greatly prolonged and the expense ofproviding eXtra plugsis avoided.

Vith these and other objects in view, the invention consists of certainnovel features of construction, and the combination and arrangement ofparts as will be more fully described and claimed.

In the accompanying drawings Figurc l represents a side elevation of aplug constructed in accordance with this invention; Fig. 2 is a centrallongitudinal section thereof; Fig. 3 is an inner end view of the plug;Fig. #l is a horizontal section taken on the line tw-'l of Fig. 2looking in the direction of the arrow. F ig. is a perspective view ofone of the annular electrodes detached.

In the embodiment illustrated, an externally threaded metal shell l isshown adapted to be removably secured `in the tappet hole or openingtherefor in the cylinder of an explosive engine, as will be readilvunderstood by those'skilled in the art. This tated when screwing thesaine into or from Serial No. l6185536.

the cylinder. The outer portion of the internal longitudinal bore of theshell 1 is enlarged and threaded thereby forming an intermediate annularinternal shoulder 3 from which the reduced portion of the bore extendsto the inner end of the shell. At its inner end this shell is preferablyformed on its inner face with an annular groove 4 which is preferablyV-shaped in cross section and is designed to receive the groundelectrode to be described. The inner edge of this end of the shell ispreferably beveled as shown at 5 to facilitate the insertion of saidground electrode.

An elongated tubular insulating plug 6 is arranged in said shell and iscomposed of any suitable material such as porcelain, liber, or the like.This insulating plug (S is formed to longitudinally and removably entera bore of the shell I and to be held therein by a hollow nut 7 throughwhich the insulating plug 'loosely `extends and which screws into thethreaded outer end ofv the bore of shell l and forces the insulatingplug inwardly in the. shell by its engagement with an annular shoulder 6formed on said plug intermediately of its' ends. This nut holds theinsulating plug at its limit of inward movement preferably against apacking or cushioning ring 8 seated against the shell seat or shoulder3. This packing ring 8 surrounds the reduced inner portion of the skirtof the insulating plug'and is seated against tliedared or inclinedannular exterior shoulder 9 formed -on said plug at a point below theshoulder 6". This packing may be formed of asbestos or any suitablematerial. The reduced inner end portion of the insulating plug G formsan annular skirt l0 arranged concentrically within the reduced portionof the bore of the shell and terminates shortof the inner end of theshell and forms an annular fluid compression chamber within the shellaround said skirt which extends from the open inner end of the shelllongitudinally thereof to the packing washer 8. bore of the plug Gextends throughout the length thereof and the inner end of this vbore isenlarged, the side walls thereof be ing preferably flared to form acompressed fluid cavity or chamber 11 open at the inner end of the plugand forming the hollow interior of the skirt 10 terminating at the in?tei-mediate internal annular seat or shoulder l2 within the pluO'.

The longitudinal A conducting stem .or-"rod 13 screiv threadedthroughout the greater portion of its length extends through the boreofthe insulating plug 6 and projects beyond ,thev

12 of the plug to limit the outward movement of the stem in the plug.This stem 13 is held in place by a cap 16 removably fitted on the outerend of the insulating plug 6 and screwed on the projecting end of thestem 13. The outer end of this stem 13 extends some distance beyond saidcap to receive certain elements hereinafter to be described.

'A shell 17 constructed of pressed. fiber or other insulating materialYtelescopically engages the upper portion of the insulating plug 6 andis exteriorly screw threaded at its lower or inner end and engages witht'he interior,- thread on the outer end of the shell 1 outside the nut 7and is securely locked ini: position thereon by nuts 18 and 19 securedon the outer end of the stem 13 which projects through an aperture inthe outer end of the shell 17, said nuts being designed to hold theshell 17 rigidly connected Arelatively to the insulating plug 6. Thisshell 17 is designed to serye as a protoet-ing device and to doublyinsulate the conducting stein or rod 13.

Suitable packing rings 20 and Q1 are arranged around the plug 6, thering 20 being arranged between the outer face of the nut 7 and the-innerend of the shell 17 and the ring 21 between the inner face of 'the nut 7and the shoulder 6. These packing rings 20 and 21 provide for theexpansion and contraction to which these plugs are subjected owing tothe extreme changes in the te1nperature to which they are exposed. Thenuts 18 and 19 are also designed to seri/'e as binding nuts by Which theelectric conductors from the magneto7 vibrating coil box or othersuitable source of high frequency electric current, While the returncurrent is made through the shell and engine cylinderl as usual or insome other suitable inanner. The nut 7 is preferably provided in itsouter edge with a plurality of notches as shown at 7 in F ft which aredesigned to receive a specially constructed Wrench to yprovide for theturning of the nut below l the outer edge of the shell 1.

' The ground terminal 22 is constructed from nonecorrosive Wire in theformof a split ring and is designed to be seated in the groove l formedin the inner face near the inner end of the shell 1, said ring beingsliffhtlj.' larger i in which it Le z n e is designed to be seated causeit ,to spring incase? tightly into place and the beveled edge 5 of theshell 1 facilitates the insertion of said electrode. i

The disk let is provided with a peripheral groove Q3 preferably V-shapedin cross section and forms a seat for the high tension electrode 2lwhich is also constructed of non-corrosive Wire in the form of a splitring which is a trifle smaller than -its seat to cause it to springtightly into place7 the resiliency of the ring holding it securelyWithin the V-shaped groove 22. This disk 1i is also preferably providedwith tivo or more recesses 1t in its outer face to provide for theinsertion therein of an instrument to hold said disk against turningWhile the nuts at the other end of the rod are being tightened. Thisdisk 141 is adjustable by means of the threaded rod 13 to which it isfixed and such adjustment p1o vides for the projection of the diskbeyond the shell 1 to permit ready changing of the electrode 2iand alsoto vary the position of the disk relatively to the skirtl 10 and theelectrode 22.

The electrodes being annular in shape and constructed from Wire of agage that will provide the proper space between the two electrodes whenplaced in the plug and properly adjusted. the distance between saidelectrodes Will be equal at all points and permit the current tol jumpacross from one to another at any point on the periphery of the centerelectrode. As the circumference is a little greater than three times thediameter, a large sparking surface will be obtain-ed. Thesering-shaj'icd electrodes are also interchangeable rendering it possibleto change thorn at any time thereby extending the life of the plug andavoiding the exp-ense and trouble of being constantly provided withextra sets of plugs.

By employing curved surface electrodes of such formation as to producean annular spart gap of uniform Width throughout7 the potential betweenthe tufo electrodes will be approximately equal completely around thespark gap for the production of an electrical discharge across said gapcon-4 sisting of a plurality of sparks distributed around the gap. Acondenser eiliect is produced by forming the opposing surfaces of theelectrodes curved or rounded and smooth, that is, Without angular orsharp edges, points, projections or roughness. lWhen the opposingelectrode surfaces are thus smooth and curved the sparks can jump ineither direction across the spark gap, and the electrical energy isstored or held back to attain the high potential necessary to produce'an exceedingly rich electrical discharge of hif'li caloric value andefficiency for'ignition j l poses. I find that peculiarly advantageousresults and increased eiliciency are atta-ined in the operation ofinternal combustion engines by the employment. of spark plugs orignition devices embodying electrical condensers composed of theopposing electrodes and the intervening igniting spark gaps. IVith suolia condenser, a spark gap of the desired Width can be attained and evenwith an excess of oil and carbon on the condenser electrodes theexceedingly rich sparks are given oil' and the intensity thereof seemsto be increased by the presence and combustion ofthe oil and carbon.

To form the electrical condensernthe opposing surfaces ot the electrodesare rounded or curved and all .tine points or roughness which mightpermit current leakage and thus prevent the condenser action on saidsurfaces, are removed. In the example shown, the two chambers formed inthe shell around and Within the depending skirt 21 have annular outletsbetween the lower edge of the skirt. and the opposing electrodes, andthe out rush of fluid from these chambers on the ignition of the chargeis thus caused to sweep the lower edge of said skirt with a scavengingaction as well as the electrode surfaces in passing through the annularspark gap. This outrush of fluid will tend to break and remove bridgesof carbon and oil that might form across the spark gap and aid in thecombustion thereof by the exceedingly rich sparks produced by thecondenser. The position of the high tension electrode 2l with respect tothe opposite electrode and with respect to the end of the insulatingskirt l() may be varied by separating the parts and changing theposition of the stop nut 15.

From the foregoing description, taken in -connection with theaccompanying drawings, the construction and operation of the inventionwill be readily understood Without requiring a more extendedexplanation.

Various changes in the form, proportion and the minor details ofconstruction may be resorted to Without depart-ing from the principle orsacrilicing any of the advantages of the invention claimed.

Having thus described my invention, what I claim is A spark plugcomprising a shell having an annular groove formed at one end thereof,an electrode in the form of a split ring arranged in said groove withthe inner face of said ring projecting beyond the edges 'of said groove,a longitudinally adjustablev disk mounted in said shell and of lessdiameter than the annular electrode secured in said shell, said diskhaving a peripheral groove, and an opposing electrode in the form of asplit ring mounted in the groove of said disk with its peripheryprojecting beyond the edges of said groove and spaced from saidfirst-mentioned elect-rode.

In testimony whereof I have hereunto set my hand in presence of twosubscribing Witnesses.

GEORGE ORVILL TERRY.

Witnesses:

JnNNin ANDERSON, G'Us'r GALETMAN.

